Molecular-dynamics simulations were used to investigate the storage capacity of hydrogen in single-walled carbon nanotubes (SWNT's) and the strain of nanotube under the interactions between the stored hydrogen molecules and the SWNT. The storage capacities inside SWNT's increase with the increase of tube diameters. For a SWNT with diameter less than 20 ?, the storage capacity depends strongly on the helicity of a the SWNT. The maximal radial strain of SWNT is in the range of 11%-18%, and depends on the helicity of the SWNT. The maximal strain of armchair SWNT's is less than that of zigzag SWNT's. The tensile strengths of SWNT's decrease with increasing diameters, and approach that of graphite (20 GPa) for larger-diameter tubes.

The growth of narrow single-wall carbon nanotubes through adduction of small carbon clusters is studied using a molecular-dynamics simulation method. Statistical behavior of the growth and defect formation process is analyzed. For C2 dimer colliding onto the side-wall of narrow single-wall nanotubes, it is very easy to get the dimer to be incorporated into the network of the tube during annealing, forming localized topological defects. During long-time annealing at 2300K, thermal fluctuation can cause structural switching among different metastable states and thereby result in energy pulses in the energy vs time curve.

The stopping power of slow antiparticles penetrating electron gases are evaluated within a scattering theory approach to the energy-loss problem. The required effective scattering potential is obtained from a selfconsistent density-functional calculation. A relationship of the stopping power Sα|Z|b (b is in the range of 0.7-0.9) at low velocities is found, in contrast to the Z2 dependence predicted by the linear-response theory. The diffuse distribution of partial wave contributions of screening electrons in the case of antiparticles is quite different from that for normal particles and is thought to be the main reason for the monotonic increment of the stopping power as a function of |Z|.

A model of an ion embedded in jellium is presented. The static charge state of a heavy ion is determined self-consistently. The effective charge of a heavy ion at low velocities is calculated, which is incorporated with the Brandt-Kitagawa effective charge theory to take the velocity dependence of the effective charge into account. The quantal harmonic oscillator model is generalized to calculate the electronic energy loss of heavy ions colliding with a carbon target. The results are compared with available experimental data.